Western University Scholarship@Western Electronic Thesis and Dissertation Repository 4-27-2021 11:00 AM Theories: Reconsidering Ramsey in the Philosophy of Science John D. Lehmann, The University of Western Ontario Supervisor: DiSalle, Robert, The University of Western Ontario A thesis submitted in partial fulfillment of the equirr ements for the Doctor of Philosophy degree in Philosophy © John D. Lehmann 2021 Follow this and additional works at: https://ir.lib.uwo.ca/etd Part of the Philosophy of Science Commons Recommended Citation Lehmann, John D., "Theories: Reconsidering Ramsey in the Philosophy of Science" (2021). Electronic Thesis and Dissertation Repository. 7834. https://ir.lib.uwo.ca/etd/7834 This Dissertation/Thesis is brought to you for free and open access by Scholarship@Western. It has been accepted for inclusion in Electronic Thesis and Dissertation Repository by an authorized administrator of Scholarship@Western. For more information, please contact [email protected]. Abstract This work is an analysis of F. P. Ramsey’s philosophy of science. Twentieth-century philosophy of science was marked by attempts to consider the relation between scientific theories and our knowledge of the empirical world through considerations of abstract mathematical structure. Such considerations led Bertrand Russell to an account of the relation between our theoretical picture of the world and its real nature as a relation of structural similarity. Subsequently, Max Newman gave what has become a well-known logico-mathematical objection to this account. William Demopoulos recently showed that Newman’s problem applied not only to Russell’s realist account, but also to a variety of otherwise disparate accounts of theoretical knowledge. The common element underlying these accounts is a conception of theories as abstract for- mal structures. Many such accounts have incorporated key elements of Ramsey’s views, most notably the Ramsey-sentence. Moreover, Demopoulos has interpreted Ramsey’s own view of theories as sharing the essential features of those abstract views, and therefore their common problem. My analysis aims to show that this abstract conception of theories does not ade- quately characterize Ramsey’s view. Namely, his account of theories was not an attempt to do the epistemology of science in the fashion of Russell or Eddington, or of subsequent struc- turalist views that have adopted the Ramsey-sentence. I show this by a broader exposition of Ramsey’s work on the nature of theories, comparing his seminal paper with his many other remarks on the nature and purpose of theories. I begin by discussing the historical context of Newman’s objection, and a generalization of it that shows its broad applicability to abstract characterizations of theoretical knowledge. I then reconstruct Ramsey’s view of theories, to show how far it extends beyond the Ramsey-sentence picture. Finally, I discuss the relevance of this view to contemporary debates concerning realism and instrumentalism. I characterize Ramsey’s view as focused not on grounding our theoretical knowledge in abstract structure, but instead on demystifying the role of theoretical language and concepts in a theory’s application to the world. Keywords: Ramsey; Ramsey-sentences; Newman’s objection; Scientific Realism; Struc- tural Realism; Theories, William Demopoulos. ii Summary for Lay Audience This work is an analysis of F.P. Ramsey’s philosophy of science. When we think of a scientific theory, there is a plausible distinction in the vocabulary, or language, we use. On the one hand, there are statements that have to do with things we more or less directly observe; on the other hand, there are statements about theoretical entities and relations, e.g. electrons, forces, space– time curvature. This plausible distinction suggests another distinction between how we come to know or understand the two classes of statement. Theoretical knowledge seems inherently more problematical than our knowledge of things through direct observation. Twentieth century philosophy of science was marked by attempts to consider the relation between scientific theories and our knowledge of the empirical world by appealing to abstract mathematical structures. In particular, Bertrand Russell believed that an adequate notion of structural similarity could explain the relation between what we experience, and the world beyond our experiences. Max Newman gave a mathematical objection to Russell’s account. However, subsequent thinkers in the philosophy of science continued to develop accounts of theoretical knowledge that appealed to abstract mathematical structures. William Demopoulos has shown that Newman’s objection generalizes beyond Russell’s theory to oppose any view which shares specific features with Russell’s. Many such accounts have incorporated key elements of Ramsey’s views. Demopoulos has interpreted Ramsey’s work on theories as sharing the essential features of those views, and therefore their common problem. My analysis aims to show that this interpretation does not adequately characterize Ramsey’s view. I reconstruct Ramsey’s view of scientific theories from his various remarks on the nature and purpose of theories. Crucially, I argue that Ram- sey’s approach to theoretical knowledge does not share the problematical features that make it vulnerable to Newman’s objection. Finally, I discuss the relevance of the reconstructed view I provide to some nearby issues in contemporary philosophy of science. iii Acknowledgements This project was funded by the Social Sciences and Humanities Research Council of Canada. I have benefited continuously from the support and encouragement of my supervisor Robert DiSalle. He has been incredibly generous with his time, and I’m grateful for all the many happy hours we’ve discussed these, and other, topics. I consider myself fortunate to have had such an outstanding philosophic role model. I can’t imagine a better mentor or supervisor. I little expected that when I knocked on John Bell’s door, looking for some help with set- theory, that he would turn into one of my dearest friends. His enthusiastic encouragement and support of my fledgling interest in mathematical logic and philosophy of mathematics has meant more than he surely realizes, not least for the confidence it fostered. I dedicate this thesis to my parents, and my wife Kate. Their love and support has meant the world to me. iv Contents Abstract ii Summary for Lay Audience iii Acknowledgements iv 1 Introduction 1 1.1 Context . 1 1.2 Overview . 4 2 The origins and applications of Newman’s objection 6 2.1 Newman’s objection contra Russell . 6 2.1.1 Russell on the external world . 6 2.1.2 The objection . 8 2.2 A mathematical interlude . 11 2.2.1 Preliminaries . 11 2.2.2 Isomorphisms . 12 2.2.3 Push–Through . 13 2.3 Three Views of Theoretical Knowledge: A critical exegesis . 14 2.3.1 Context of the paper . 15 2.3.2 Overview . 16 2.3.3 Target of the analysis . 17 2.3.4 All that business about toy models and Craig transcriptions . 18 2.3.5 Demopoulos reading Russell . 19 2.3.6 Demopoulos reading Ramsey . 21 2.3.7 Demopoulos reading Carnap . 24 2.3.8 Demopoulos’ conclusion and suggestion . 25 2.4 Newman’s objection applied to Eddington . 28 2.4.1 Summary of The Philosophy of Physical Science . 28 2.4.2 Braithwaite and Solomon’s criticism . 32 2.5 Newman’s objection applied to Ramsey-sentence structures . 35 2.6 Summary . 37 3 Ramsey and Theories 39 3.1 Theories ...................................... 40 3.1.1 Responding to Russell: What Physics Says . 40 v 3.1.2 Exegesis of Theories ........................... 43 Theories and Languages . 44 Question and Answer . 46 3.2 General Propositions, Causal Considerations . 55 3.2.1 “General Propositions and Causality” . 55 3.2.2 “Causal Qualities” . 59 3.2.3 Drawing Together . 60 3.3 Summary . 65 4 Structure, more broadly 67 4.1 Scientific Realism, Instrumentalism, and Ramsey . 68 4.2 Structuralism without metaphysics? . 71 4.3 Extending “Theories” . 75 4.4 Summary . 87 5 Conclusion 89 Bibliography 94 vi Chapter 1 Introduction Twentieth-century philosophy of science was marked by attempts to understand the relation between scientific theories and our knowledge of the empirical world through considerations of abstract mathematical structure. Such considerations led Bertrand Russell to an account of the relation between our theoretical picture of the world and its real nature as a relation of structural similarity. Subsequently, Max Newman gave what has become a well-known logico-mathematical objection to Russell’s account. This critique indicated that the notions of mathematical structure and structural similarity Russell used are too abstract to be informative. William Demopoulos recently showed that Newman’s objection applied not only to Russell’s realist account, but also to a variety of otherwise disparate accounts of theoretical knowledge. The work of F.P. Ramsey has played an important role in the history of those accounts. This study seeks to reassess Ramsey’s work in light of its historical context and its significance to contemporary philosophy of science. 1.1 Context Russell represents an historical attempt to account for the classic problem of the relation between appearances and reality by applying our understanding of mathematical structure to the problem. Kant thought that we can only know things as they appear to us, according to our forms of intuition and categories of understanding, and not as they are in themselves. Russell sought to provide a framework in which he could articulate a notion of similarity that would re- spond to the Kantian limitation to understanding the world outside our acquaintance. He argued that the world really has a mathematical structure, and theories succeed to the extent that they provide models that are structurally similar to the structure represented by our sensations. In Kantian terms, Russell sought to provide a way to relate the phenomenal and noumenal worlds, or things as they appear to us and things in themselves.